What is Iran's Revolutionary Guard, the paramilitary on the EU "terrorist list"?

Created in the aftermath of the 1979 Islamic Revolution - the Islamic Revolutionary Guard Corps is now the most powerful organization in Iran. A parallel military force - the regime's armed wing and a major economic player - it plays a central role in repressing demonstrations, like in the widespread protests which took place recently and were submitted to a deadly crackdown. Now, the EU has inscribed the organisation on its "terrorist list". Who exactly are they?

What is Iran's Revolutionary Guard, the paramilitary on the EU "terrorist list"?
Created in the aftermath of the 1979 Islamic Revolution - the Islamic Revolutionary Guard Corps is now the most powerful organization in Iran. A parallel military force - the regime's armed wing and a major economic player - it plays a central role in repressing demonstrations, like in the widespread protests which took place recently and were submitted to a deadly crackdown. Now, the EU has inscribed the organisation on its "terrorist list". Who exactly are they?